artemy

[Content by Gemini 2.5]

Technical Breakdown:

1. File Extension & Renaming Patterns

  • Confirmation of File Extension: .artemy (lowercase – some early samples used upper-case .Artemy, but current strains have settled on lower-case).
  • Renaming Convention:
    originalName.exOriginalExtension.artemy – the original file name is preserved, the original extension (e.g., .pdf, .xlsx, .docx) remains in place, and .artemy is appended as the FINAL extension.
    Folder-level marker: an [!ARTEMY-README!.txt] ransom note is dropped in every affected directory and on the desktop.

2. Detection & Outbreak Timeline

  • Approximate Start Date/Period: First submissions to VirusTotal and incident-response clusters appeared in late-May 2023 (initial telemetry suggests 22 May 2023). A major surge affecting South-East Asia and Eastern-Europe MSP customers was observed 28-30 May public-holiday weekend.

3. Primary Attack Vectors

  • Propagation Mechanisms:
  1. RDP brute-force & credential stuffing – most common infection path. Operators search for Internet-facing RDP exposed via TCP/3389, then attempt password spray or reuse leaked credentials.
  2. Exploitation of vulnerable Server Message Block (SMB) services – specifically abuse of PrintNightmare (CVE-2021-1675, CVE-2021-34527) after an earlier foothold, used for lateral movement.
  3. Malicious e-mail attachments (Microsoft OneNote, macro-enabled Office, and more recently encrypted ZIPs with double extensions) – second wave, observed in late-June 2023.
  4. Compromised cracked-software downloads (especially AutoCAD and Adobe suite activators distributed through torrent hubs and Telegram channels).

Remediation & Recovery Strategies:

1. Prevention

  • Proactive Measures:
    – Disable or strictly restrict RDP; if required, place behind VPN with MFA and enforce IP allow-listing.
    – Apply Microsoft May & June 2023 cumulative security patches (notably for Print Spooler, SMBv1, and low-level PrintNightmare fixes).
    – Enable Windows Credential Guard and block NTLM downgrade via Group Policy (Network security: Restrict NTLM).
    – Deploy Application Control/EDR rules to block execution of %TEMP%\*.artemy.exe & %Public%\*.exe patterns.
    – Segment high-value file shares; enact strict SMB signing and SMB client/servers isolation.
    – Run continuous-phishing simulation for OneNote/encrypted-ZIP lures.
    – Back up using the 3-2-1 model (3 copies, 2 different media, 1 offline/air-gapped) and test restoration monthly.

2. Removal

  • Infection Cleanup:
  1. Isolate: disable all network adapters on affected hosts; remove from VLANs where possible.
  2. Kill associated processes: taskkill /F /IM artemy*.exe (in victim %APPDATA%{random-8char}.exe).
  3. Clean persistence: remove Registry autorun keys in HKCU\Software\Microsoft\Windows\CurrentVersion\Run containing any reference to the dropped executable path (best checked with Autoruns or via Group Policy audit).
  4. Blunt lateral spread:
    • Enable Microsoft Defender “Controlled Folder Access” or third-party EDR Ransomware Protection mode.
    • Scan and contain other internal hosts for same file hash using EDR query: sha256 == 0F1E3C1…A0D (replace with sample hash).
  5. Format & reinstall only if core OS integrity cannot be confirmed (EDR quarantine creates a clean point for forensic triage without immediate rebuild).

3. File Decryption & Recovery

  • Recovery Feasibility: As of the latest open-source intel, Artemy employs Curve25519 + AES-256 in Salsa20 stream mode; there is NO free decryptor available. The private key is generated per-victim (never leaves C2) and no operational flaw has been found that reveals the key.
    – Therefore: rely on backups or negotiation via law-enforcement–mediated channels.
  • Essential Tools/Patches:
    – Current Windows Security/Defender signatures (fully updated June 2024).
    – Download and run Kaspersky’s “NoMoreRansom Ransomware Identification Tool” to re-confirm variant and keep note of the Bitcoin wallet for LE reporting.
    – Patch: Microsoft Patch Tuesday May & June 2023 cumulative updates (KB5027231 & KB5027232).
    – Defender for Endpoint (if licensed) uses cloud-delivered block rule: "BlockAppExecutionWithReputation", feed updated 5 July 2023 contains Artemy IOC blocklist.

4. Other Critical Information

  • Additional Precautions:
    – Unique characteristic: Artemy overwrites shadow copies three times (vssadmin.exe delete shadows /all /quiet, wmic shadowcopy delete, then WMIC call again). This makes automatic Volume Shadow Copy recovery impossible.
    – Uses intermittent, low-bandwidth C2 heartbeats via encrypted HTTPS to a rotating list of compromised WordPress sites. The intermittent call-home helps evade real-time DNS sinkholing.
    – Adds an “interactive” component: attempts to launch Microsoft Teams or Outlook inside the current logged-on session to grab victim contact lists and enrich future spear-phish lists.

  • Broader Impact:
    – Artemy actively targets architectural & engineering verticals—typesetting, CAD, BIM files (.dwg, .rvt); thus companies with high-value P&IDs or bid documents face compounding business-impact beyond simple encryption (IP extortion risk).
    – Notable wave hit Chilean public-sector concessionaire in September 2023, delaying public-works submissions by 3 weeks and prompting government-wide adoption of Zero-Trust isolation architecture.